Fuel nozzle assembly with removable components

ABSTRACT

A fuel nozzle assembly ( 10 ) for a gas turbine engine ( 12 ) is provided. The fuel nozzle assembly ( 10 ) includes a rocket unit ( 14 ) and a flow-guiding element, such as may include swirler elements, non-swirler elements, or a combination of swirler elements and non-swirler elements, with an aft end ( 18 ) in threaded engagement with a forward end ( 20 ) of the rocket unit ( 14 ). The fuel nozzle assembly ( 10 ) may include an oil tip ( 36 ) including a clocking feature with a mechanical constraint to orient the oil tip ( 36 ) at a predetermined angular orientation ( 42 ) relative to the swirler ( 16 ). The fuel nozzle assembly ( 10 ) may include one or more gas stage inlets ( 13, 15 ), one or more oil stage inlets ( 17, 19 ), and a flexible hose ( 26 ) to direct the oil to a plurality of rocket units ( 14 ).

This application claims benefit of the Jun. 3, 2014 filing date of U.S.application Ser. No. 14/294,526 which is incorporated by referenceherein.

FIELD OF THE INVENTION

The invention relates to gas turbine engines, and more particularly to afuel nozzle assembly of a combustor of a gas turbine engine.

BACKGROUND OF THE INVENTION

FIG. 1 illustrates a conventional fuel nozzle assembly 110 for a gasturbine engine. The fuel nozzle assembly 110 includes various componentsthat are welded or brazed together, such as oil tips 136 that are weldedto swirlers 116, where the oil tips 136 have a predetermined angularorientation, for optimal oil atomization and combustion performance.Additionally, the swirlers 116 are welded to rocket units 114, where theswirlers 116 have a predetermined angular orientation, for optimalaerodynamics. However, in the event that repair or replacement of theoil tips 136 or the swirlers 136 is needed, one or more of these weldedconnections must be dismantled, necessitating a complete disassembly andreassembly of the entire fuel nozzle assembly 110, and involvingextensive cost and turnaround time.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of thedrawings that show:

FIG. 1 is a cross-sectional side view of a conventional fuel nozzleassembly used in a gas turbine engine;

FIG. 2 is a side perspective view of a fuel nozzle assembly of a gasturbine engine;

FIGS. 3A-3B are cross-sectional side views of a rocket unit-swirlerinterface of the fuel nozzle assembly of FIG. 2;

FIG. 3C is a cross-sectional end view of the rocket unit-swirlerinterface of FIG. 3B along the line 3C-3C;

FIG. 4 is a cross-sectional side view of a fuel nozzle-rocket unitinterface of a fuel nozzle assembly used in a gas turbine engine;

FIG. 5 is a cross-sectional side view of a swirler-oil tip interface ofthe fuel nozzle assembly of FIGS. 3A-3B; and

FIG. 6 is an exploded view of the swirler-oil tip interface of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

Based on the above-discussed limitations of the conventional fuel nozzleassembly 110, the inventors recognized that if the oil tips and theswirlers were more easily removable from the fuel nozzle assembly, theoil tips or the swirlers could be repaired or replaced without the needto disassemble and reassemble the entire fuel nozzle assembly. Thus, theinventors recognized that removable oil tips and removable swirlerswould significantly reduce the repair or replacement cost and turnaroundtime. Based on these recognitions, the inventors developed structuralfeatures for each of the oil tips and swirlers, to removably secure theoil tips and the swirlers within the fuel nozzle assembly. Additionally,in order to maintain the oil tips and the swirlers at their respectivepredetermined angular orientation, the inventors developed a respectiveclocking feature, to ensure that the oil tips and the swirlers areoriented at their respective predetermined angular orientation, whenremovably secured within the fuel nozzle assembly. It will beappreciated that aspects of disclosed embodiments are not limited toflow-guiding elements comprising swirler elements (swirlers) sincenon-swirler elements could also be used, depending on the needs of agiven application. For example, certain embodiments may includeflow-guiding elements comprising non-swirler elements in combinationwith (or in lieu of) swirlers. Accordingly, without limitation, aspectsof the present invention, such as the foregoing structural features, asmay include clocking features, may be used with flow-guiding elementscomprising swirler elements, non-swirler elements, or a combination ofone or more swirler elements and one or more non-swirler elements.

FIG. 2 illustrates a fuel nozzle assembly 10 for a gas turbine engine12. The gas turbine engine 12 is capable of operation on a gas or oilfeed such that the fuel nozzle assembly 10 includes a pair of gas stageinlets 13, 15, for use when the engine operates in a gas mode and a pairof oil stage inlets 17, 19, for use when the engine operates in an oilmode. However, the embodiments of the present invention are not limitedto dual-fuel nozzles, and are applicable to single-fuel gas turbineengines, such as gas or oil turbine engines, for example. Flexiblehosing 26 is used to connect the oil stage inlets 17, 19 to a pluralityof staged rocket units 14 through a cover plate 21. In an exemplaryembodiment, the flexible hosing 26 may be made from stainless steel 316Lmaterial, for example. A plurality of flow-guiding elements, such asswirlers 16 are removably connected to the rocket units 14, in a mannerdiscussed in greater detail below, to receive fuel from the rocket units14 and to deliver a swirled mixture of air and fuel to a combustionchamber (not shown). As noted above, the flow-guiding elements may benon-swirler elements in combination with (or in lieu of) swirlers. Inthe specific embodiment of FIG. 2, eight staged rocket units 14 andeight staged swirlers 16 are provided in two stages and thus four piecesof flexible hosing 26 connect each oil stage inlet 17, 19 to four rocketunits 14 of each stage. However, this specific staged arrangement isexemplary and the embodiments of the present invention are not limitedto any specific number of rocket units or stages in a fuel nozzleassembly.

FIGS. 3A-3C illustrate an interface between a forward end 20 of therocket unit 14 and an aft end 18 of the swirler 16 of the fuel nozzleassembly 10. As illustrated in FIG. 3B, the interface between the rocketunit 14 and the swirler 16 includes a flat portion 58 of the aft end 18of the swirler 16 engaged with an inner surface of a flat portion 59 ofthe forward end 20 of the rocket unit 14. FIG. 3C illustrates across-sectional end view of this interface, with the flat portion 58 ofa circumference 56 of the swirler 16 radially oriented with the flatportion 59 of a circumference 57 of the rocket unit 14. Thus, the flatportions 58, 59 acts as a clocking feature with a mechanical constraint,to orient the swirler 16 at a predetermined angular orientation 54 (FIG.2) relative to the rocket unit 14. In an exemplary embodiment, the flatportions 58, 59 orient the swirler 16 within an angular tolerance of thepredetermined angular orientation 54, such as within +/−1 degree, forexample. As illustrated in FIG. 3C, the diameter of the flat portion 59of the forward end 20 of the rocket unit 14 exceeds the diameter of theflat portion 58 of the aft end 18 of the swirler 16 by a radialclearance 61. In an exemplary embodiment, the radial clearance 61 isless than a threshold clearance, such that the flat portions 58, 59 actas the mechanical constraint to maintain the radial orientation of theswirler 16 at the predetermined angular orientation 54 (FIG. 2). Theflat portion 58 around the circumference 56 of the aft end 18 of theswirler 16 is radially aligned with a flat portion 63 (FIG. 2) around acircumference of an outer surface of the swirler 16. As illustrated inFIG. 2, the predetermined angular orientation 54 of the swirler 16aligns the flat portion 63 on the outer surface of the swirler 16 with aflat portion 60 on an outer surface of an adjacent swirler 16, such thatthe plurality of swirlers 16 align and fit within the radial plane ofthe fuel nozzle assembly 10. Additionally, as illustrated in FIG. 2, thepredetermined angular orientation 54 of the swirler 16 orients the vanes23 of the swirler 16 at predetermined radial positions, for enhancedaerodynamics. Although FIG. 3C depicts that the swirler 16 is aligned inthe predetermined angular orientation 54 by aligning the flat portions58, 59 of the swirler 16 and the rocket unit 14, the embodiments of thepresent invention may utilize any type of clocking feature with amechanical constraint, to orient the swirler 16 at the predeterminedangular orientation 54.

After aligning the swirler 16 at the predetermined angular orientation54, the swirler 16 is removably secured to the rocket unit 14. Asillustrated in FIGS. 3A-3B, the aft end 18 of the swirler 16 includes anouter radial lip 66 from which the flat portion 58 extends a distance 71aft to a tip 72. The forward end 20 of the rocket unit 14 includes aninner radial lip 70 from which the flat portion 59 extends a distance 73forward to a tip 68. As illustrated in FIG. 3B, the distance 71 isgreater than the distance 73. A seal 64, such as a C-seal, for example,is positioned between the tip 68 of the forward end 20 of the rocketunit 14 and the outer radial lip 66 of the aft end 18 of the swirler 16.The gas passage between the rocket unit 14 and the swirler 16 is sealedwith the C-seal 64. Additionally, vibrations at the interface of therocket unit 14 and the swirler 16 during operation of the fuel nozzleassembly 10 are absorbed over the distance 73, due to the small radialclearance 61, i.e. the swirler 16 does not vibrate independent of therocket unit 14. The seal 64 is compressed by a predetermined amount,when the tip 72 of the aft end 18 of the swirler 16 makes contact withthe inner radial lip 70 of the forward end 20 of the rocket unit 14. Inan exemplary embodiment, during a casting or machining of the swirler 16and the rocket unit 14, the distances 71, 73 may be subject to a tightcontrol tolerance, such that the seal 64 is compressed by thepredetermined amount when the tip 72 makes contact with the inner radiallip 70. In order to move the tip 72 of the aft end 18 of the swirler 16in an aft direction and into contact with the inner radial lip 70, a nut44 is provided in threaded engagement with the forward end 20 of therocket unit 14. As illustrated in FIG. 3B, an inner radial lip 74 of thenut 44 contacts a forward side of the outer radial lip 66, so that uponthreaded engagement of the nut 44 with the forward end 20 of the rocketunit 14, the tip 72 of the aft end 18 of the swirler 16 moves intocontact with the inner radial lip 70. As further illustrated in FIG. 3B,the nut 44 includes internal threads 46 that are in threaded engagementwith external threads 48 on the forward end 20 of the rocket unit 14.Additionally, as illustrated in FIG. 3A, the nut 44 includes flatportions 45 along an outer surface, such that the nut 44 can betightened by a wrench or a similar tightening tool, for example. The nut44 engages the forward end 20 of the rocket unit 14, until the tip 72 ofthe aft end 18 of the swirler 16 makes contact with the inner radial lip70 of the forward end 20 of the rocket unit 14, indicating that the seal64 is compressed by the predetermined amount. Additionally, to preventdisengagement of the nut 44 from the rocket unit 14 during operation ofthe gas turbine engine 12, a tack weld 47 may be applied between an afttip of the nut 44 and the rocket unit 14, as illustrated in FIG. 3B.

FIGS. 3A-3B illustrate an oil tube 32 and an oil tip 36 that are used topass oil through the fuel nozzle assembly 10 operating in an oil fuelmode. However, when the fuel nozzle assembly 10 is single-fuel andoperates in a single gas mode, the oil tube 32 and the oil tip 36 arenot present, since oil is not passed through the fuel nozzle assembly10. When the fuel nozzle assembly 10 operates in the single gas mode,and the swirler 16 of the fuel nozzle assembly 10 requires repair orreplacement, the swirler 16 is removed from the fuel nozzle assembly 10with the following steps. The tack weld 47 is first removed. The nut 44is then disengaged from the forward end 20 of the rocket unit 14, bydisengaging the internal threads 46 of the nut 44 from the externalthreads 48 on the forward end 20. The swirler 16 can then be removedfrom the forward end 20 of the rocket unit 14 and either repaired orreplaced with a substitute swirler.

When the fuel nozzle assembly 10 operates in a single oil mode or in thedual-fuel mode, the oil tube 32 and the oil tip 36 are present withinthe fuel nozzle assembly 10. Before the swirler 16 can be removed fromthe dual-fuel or the single oil mode fuel nozzle assembly 10,disengagement of the oil tube 32 from the fuel nozzle assembly 10 isinitially performed and will now be discussed. FIG. 4 depicts an aft end22 of the oil tube 32 that is welded to an oil tube extension 33. A seal34 is positioned between an aft end of the oil tube extension 33 and aforward surface of an inner radial lip 29 of a compression fitting 28.An extension screw 30 engages an aft surface of the inner radial lip 29of the compression fitting 28 and engages internal threads within theoil tube extension 33, to move the oil tube extension 33 aft andcompress the seal 34 between the aft end of the oil tube extension 33and the inner radial lip 29 of the compression fitting 28, to form asealed interface. In an exemplary embodiment, the aft end of the oiltube extension 33 may include a pocket to receive the seal 34. In anexemplary embodiment, the extension screw 30 may have a hexalobularinternal drive feature with a hole through the center, to allow oil topass through, for example. In another exemplary embodiment, the seal 34may be a flat washer, for example. After the seal 34 is compressedbetween the oil tube extension 33 and the compression fitting 28, aconnection 27 of the flexible hose 26 (FIG. 2) is engaged with thecompression fitting 28, to connect the flexible hose 26 via. compressionstyle fitting.

When the fuel nozzle assembly 10 is operating in the single oil mode orthe dual-fuel mode, the swirler 16 may need repair or replacement.Initially, the oil tube 32 is disengaged from the fuel nozzle assembly10 by the following steps. The flexible hose connection 27 is disengagedfrom the compression fitting 28, by disengaging the internal threads 31on the flexible hose connection 27 from the external threads 39 on thecompression fitting 28. This step provides access to the extension screw30, which is then disengaged from the oil tube extension 33. The oiltube 32 and the oil tube extension 33 are now disengaged from the fuelnozzle assembly 10 and may be removed along with the swirler 16 thatrequires repair or replacement. Upon repairing or replacing the swirler16, the oil tube 32 and oil tube extension 33 may be reconnected to thefuel nozzle assembly 10 by engaging the extension screw 30 within theoil tube extension 33 until the seal 34 is compressed and subsequentlyengaging the flexible hose connection 27 with the compression fitting28.

FIG. 5 illustrates the oil tip 36 removably secured to the swirler 16 inthe fuel nozzle assembly 10. In addition to the swirler 16, the oil tip36 is removable from the fuel nozzle assembly 10, in the event thatrepair or replacement of the oil tip 36 is required. The oil tip 36 maybe removed for repair or replacement, irrespective of whether theswirler 16 requires repair or replacement. The oil tip 36 is removablysecured to the swirler 16 using the following steps. As illustrated inFIG. 6, the oil tip 36 is initially passed through a central opening 89in a nut 88, until a plurality of fingers 94 at a forward end 93 of thenut 88 engage an annular ramp 96 at an aft end 83 of the oil tip 36. Thefingers 94 are separated by axial slots 95, such that the fingers 94 areradially adjustable to expand over and engage the annular ramp 96. Afterthe oil tip 36 is secured within the nut 88, the oil tip 36 is radiallyoriented using a clocking feature with a mechanical constraint to orientthe oil tip 36 at a predetermined angular orientation 42 relative to theswirler 16. The oil tip 36 is radially aligned such that a radialprojection 82 of the oil tip 36 is received within one of a plurality oflobes 78 spaced by an angular interval 79 on a forward end 81 of theswirler 16, resulting in the predetermined angular orientation 42 of theoil tip 36. In the exemplary embodiment of FIGS. 5-6, twelve lobes 78are separated by an angular interval 79 of 30 degrees, such that the oiltip 36 can be oriented in 30 degree increments, for example. However,the embodiments of the present invention are not limited to any specificnumber of lobes or angular interval. In another exemplary embodiment,the lobes 78 are spaced within an angular tolerance of each angularinterval 79, such as within +/−1 degree, for example. As illustrated inFIG. 5, the oil tip 36 defines an opening 43 with radial holes 41 todirect the oil for atomization during operation of the fuel nozzleassembly 10. As appreciated by one skilled in the art, the radial holes41 may be asymmetrically arranged within the opening 43, such that idealatomization of the oil occurs at a predetermined angular orientation.After the radial projection 82 is received within the appropriate lobe78 on the forward end 81 of the swirler 16, the oil tip 36 is angularlyfixed at the predetermined angular orientation 42. The nut 88 is thenengaged with the forward end 81 of the swirler 16, such that internalthreads 90 of the nut 88 engage with external threads 92 on the forwardend 81 of the swirler 16. As the nut 88 is engaged with the forward end81 of the swirler 16, a surface 86 (FIG. 6) of the oil tip 36 moves andmakes contact with a seal 84 positioned between an annular surface 85 ofthe forward end 81 and the oil tip 36. As the surface 86 continues tomove, the seal 84 is axially compressed along the annular surface 85.The seal 84 is compressed by a predetermined amount when the surface 86makes contact with a step 87 of the forward end 81 that is positionedoutside and forward of the annular surface 85. A height of the step 87above the annular surface 85 controls the predetermined amount at whichthe seal 84 is compressed. When the seal 84 is compressed by thepredetermined amount, a forward tip of the oil tube 32 (FIG. 5) isaligned with an inlet of the opening 43 of the oil tip 36. The forwardtip of the oil tube 32 is sealed to an inner surface of the swirler 16,in a similar manner as appreciated by one skilled in the art. An aft end97 of the nut 88 may be crimped within a groove 99 along the swirler 16outer surface to secure the nut 88 and the oil tip 36 to the forward end81 of the swirler 16. The crimping of the aft end 97 may be performedwith a crimping tool that is known to one skilled in the art.

In the event that the oil tip 36 requires re-alignment, repair orreplacement, the following steps may be employed. The aft end 97 of thenut 88 is initially de-crimped from the groove 99 along the swirler 16.The nut 88 is then disengaged from the forward end 81 of the swirler 16,which causes the surface 86 of the oil tip 36 to move forward from theannular surface 85 and decompression of the seal 84. The radialprojection 82 moves out of the selective lobe 78 during the threadeddisengagement of the nut 88. If the oil tip 36 needs to be realigned,then upon threaded disengagement of the nut 88 from the forward end 81,the oil tip 36 may be realigned relative to the swirler 16, by aligningthe radial projection 82 with the appropriate lobe 78 and subsequentlyrethreading the nut 88 along the forward end 81 of the swirler 16. Ifthe oil tip 36 requires repair or replacement, the oil tip 36 may beremoved from the nut 88 and repaired or replaced with a substitute oiltip. The repaired or replaced oil tip may then be secured to the nut 88and the swirler 16 using the above steps.

While various embodiments have been shown and described herein, it willbe appreciated that such embodiments are provided by way of exampleonly. Numerous variations, changes and substitutions may be made withoutdeparting from the invention herein. Accordingly, it is intended thatthe invention be limited only by the spirit and scope of the appendedclaims.

1. A fuel nozzle assembly of a gas turbine engine, comprising: a flow-guiding element; and an oil tip including a clocking feature with a mechanical constraint to orient the oil tip at a predetermined angular orientation relative to the flow-guiding element.
 2. The fuel nozzle assembly of claim 1, further comprising a rocket unit and an aft end of the flow-guiding element in threaded engagement with a forward end of the rocket unit.
 3. The fuel nozzle assembly of claim 2, further comprising an aft end of an oil tube of the rocket unit threadably engaged to a flexible hose to the rocket unit.
 4. The fuel nozzle assembly of claim 1, wherein said clocking feature includes: a plurality of lobes separated by an angular interval around a circumference of a forward end of the flow-guiding element; and a radial projection at an aft end of the oil tip, said radial projection selectively received within one of the lobes to orient the oil tip at the predetermined angular orientation.
 5. The fuel nozzle assembly of claim 1, further comprising a seal positioned between an annular surface of a forward end of the flow-guiding element and a surface of an aft end of the oil tip, wherein the seal is compressed by a predetermined amount based on contact between the surface and a step of the flow-guiding element positioned outside and forward of the annular surface.
 6. The fuel nozzle assembly of claim 5, further including a nut with a central opening to secure the oil tip; wherein the nut includes internal threads in threaded engagement with external threads on the forward end of the flow-guiding element to initiate the contact between the surface and the step.
 7. The fuel nozzle assembly of claim 6, wherein a forward end of the nut includes a plurality of fingers separated by axial slots such that the fingers are radially adjustable to engage an annular ramp at the aft end of the oil tip.
 8. The fuel nozzle assembly of claim 1, wherein the flow-guiding element comprises a non-swirler element.
 9. The fuel nozzle assembly of claim 1, wherein the flow-guiding element comprises a swirler element.
 10. The fuel nozzle assembly of claim 1, wherein the flow-guiding element comprises a combination of at least one non-swirler element and at least one swirler element. 